Abstract: A composition for coating a surface includes a carrier and an indicator distributed throughout the carrier. The indicator is configured to modify an appearance of the coating. The indicator facilitates determining a thickness of the coating in response to the appearance of the coating.

Abstract: A surface treatment, especially for titanium and aluminum alloys, forms a pigmented sol-gel film covalently bonded on the metal surface to produce desired color, gloss, reflectivity, electrical conductivity, emissivity, or a combination thereof usable over a wide temperature range. The coating retains its characteristics and impact resistance following exposures to temperatures at least in the range from ?321° F. to 750° F. An aqueous sol containing an organometallic alkoxide containing either Ti or Al and an organosilane with an organic acid catalyst and stabilizer is applied to etched or grit blasted substrates by dipping, spraying, or drenching, to produce bonds in a single application comparable in strength and performance to standard anodize controls. The sol-gel coating may be graded in its ceramic character by adjusting the organosilane component between TEOS and silanes that have more distinctive organic character by virtue of organic ligands attached to the silicon.